Coaxial cable connector

ABSTRACT

A connector for coaxial cables suitable for use on a group of cables having the same impedance characteristics and similar nominal size but different structural details. A backshell of the connector which is sufficiently large to receive each cable of the group fastens to a body which contains a mass of dielectric material in which a central conductor contact is fitted. A seat and collar with complementary frustoconical surfaces adapted to receive an outwardly and forwardly flared end of the outer conductor of the cable are positioned generally within the transition between the backshell and the body. Complementary fastening means on a body and the backshell force the collar and seat together against the flared end of the outer conductor.

O United States Patent 1 3,678,446 Siebelist [45] July 18, 1972 COAXIALCABLE CONNECTOR I Primary Examiner-Marvin A. Champion [72] Inventor.Hilbert R. Slebelist, Las Vegas, Nev. Amman Examiner Lawrence J. swab[73] Assignee: The United States or Amerlca as At n y-R an A- An nrepresented by the United States Atomic Energy Commisslon [57] ABSTRACT[22] Filed: June 2, 1970 A connector for coaxial cables suitable for useon a group of cables having the same impedance characteristics andsimilar [21] 42636 nominal size but different structural details. Abackshell of the connector which is sufficiently large to receive eachcable of 52] us. or. ..339/177 E, 174/89 c the E P fastens a My whichcmaihs a mass dielecmc 51 Int Cl n. 17/04 material in which a centralconductor contact is fitted. A seat [58] Field of Search ..339/60 c 89 c90 c 91 P and with cmplememafy frusmmical Surfaces adapted 339/94 C, 177R 177 to receive an outwardly and forwardly flared end of the outerconductor of the cable are positioned generally within the 56 R ftransition between the backshell and the body. Complemental e mum Citedry fastening means on a body and the backshell force the col- FOREIGNPATENTS OR APPLICATIONS lar and seat together against the flared end ofthe outer con- 'd 1 1,075,699 2/1960 Germany ..339/177 R or 232,9792/1961 Australia ..l74/89 5 Claims, 1 Drawing figure 24 so 54 4s 70 7232 as BACKGROUND OF THE INVENTION The invention described herein wasmade in the course of, or under contract AT(29-2)-20 with the US. AtomicEnergy Commission.

This invention relates to connectors for coaxial cables of the RF (radiofrequency) type.

The use of coaxial cables in the transmission of intelligence by way ofthe propagation of electromagnetic energy is well known. It is also wellknown that the maintenance of uniform impedance characteristicsthroughout the transmission path is essential in order to minimizedistortion of the intelligence during transmission. Accordingly, coaxialcables are designed and manufactured to certain standardized incrementsof impedance characteristics such as 50 ohms, 75 ohms, 100 ohms, etc.,to which other components of an intelligence link, i.e., transmitter,receiver, amplifier, etc., also conform.

In some applications in which coaxial cables are used, the environmentsto which various portions of the transmission link are exposed aredrastically different. One such applica tion is in the telemetrynetworks utilized in connection with testing nuclear explosives. Aportion of the link may be required to withstand high temperature.Another (or same) portion may be required to have high mechanicalstrength in order to support its own weight over many feet, such as whenthe test is of an explosive emplaced for detonation thousands of feetbelow the surface of the earth. High mechanical strength may also berequired in portions of the links placed on the surface of the ground inplaces where surface vehicles may on occasion run over them. Someportions of the links may need to be gas tight, moisture proof, orsatisfy any number of other criteria. On the other hand, there may besignificant portions of particular transmission links where very minimalphysical characteristics are adequate.

The particular service environment to which a cable is designed will, ofcourse, affect its cost. When it is realized that one nuclear test mayentail the use of a thousand or more individual telemetry links, eachtraversing thousands of feet, it can be appreciated that considerablesavings can be realized by the selection of a number of cables ofdiffering physical characteristics to satisfy particular requirements ofthe various portions of each telemetry link. However, a large number ofindividual criterion for cable applications as well as individualmanufacturing preferences and/or techniques of cable manufacturers hasresulted in a proliferation of cable configurations.

For instance, a single manufacturer provides five different cables of 50ohm impedance and seven-eights inch nominal diameter. Each of these fivecables has its own advantages with respect to each of the others. Theinner diameter (ID) of the outer conductor varies from 0.795 to 0.965inch and the outer diameter (O.D.) from 0.948 to 1.005 inches for thesefive cables. Four of the five have heliax outer conductors. The outerdiameter of the inner conductor, which in the case of this manufacturerare all tubular, varies from 0.312 to 0.358 inch. There is only oneduplication in this group of five with respect to all conductordimensions. Another manufacturer provides three cables in this samenominal size and impedance characteristic. Each has non heliax outerconductors having an CD. of 0.875 inch and an ID. varying from 0.758 to0.801 inches. Each of these three has a solid core inner conductor, thevO.D. of which varies from 0.288 to 0.300 inch. When the total number ofmanufacturers, nominal cable sizes, and impedance ratings areconsidered, it can be seen that the number of individual cablesavailable is truly legion.

The problem of supplying connectors for this multitude of cables is notinsignificant. It can be appreciated that the costs involved inprocuring, maintaining inventory, and other handling for a multitude ofdifference cable connectors can be very significant, and particularly sofor large users of cables. It has been only in relatively recent yearsthat a number of standard interfaces for coaxial cable connectors havebeen developed in order to insure that, for example, all 50 ohm ca Ibles (within certain size limitations) can be connected together,provided the connectors used with them incorporate a particular standardinterface. However, generally speaking, each particular cable hasutilized a different connector with a backshell designed for attachmentonto that particular cable configuration and essentially none other.Accordingly, a user of all eight of the cables alluded to above has inthe past had to procure, warehouse, handle, etc., seven different cableconnectors.

SUMMARY OF INVENTION Accordingly, it is an object of this invention toprovide a cable connector which permits one connector to be suitable foruse on a group of coaxial cables having the same impedancecharacteristics and the same or similar nominal size, but havingdifferent structural details. Briefly summarized, this and additionalobjects of the invention are accomplished by a connector with abackshell having an inner cylindrical surface of larger diameter thanthe outer conductor of the largest of the group of cables, and a bodywith an inner cylindrical surface with a diameter larger than thatfastened to the forward end of the backshell. The body contains a massof dielectric material within which is fitted a central conductorcontact which receives the inner conductor of the cable. Complementaryfrustoconical surfaces on a seat and a collar, positioned longitudinallybetween the two inner cylindrical surfaces, generally traverse theradial distance between the two inner cylindrical surfaces. An outwardlyand forwardly flared end portion of the outer conductor of the cable isreceived between these frustoconical surfaces of the seat and collar.Complementary fastening means on the body and the backshell fasten thebody and backshell together and force the frustoconical surfaces againstthe flared end portion of the outer conductor of the cable.

BRIEF DESCRIPTION OF DRAWING The single FIGURE of drawing is alongitudinal section of a coaxial cable connector in accordance with theinvention, with an end of a cable to be connected and a standardinterface inner contact assembly shown in exploded, broken awayrelationship.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to the single FIGURE ofdrawing, the connector 10 in accordance with the invention is shown inconjunction with interface inner contact assembly 12 and coaxial cable14, each of the latter two shown in exploded away relationship fromtheir connection positions. The major components of connector 10 arebackshell 16 and body 18 which are joined together by suitable meanssuch as complementary screw threads 20, body 18 being the male member.Snugly fitted within body 18 is a mass of dielectric material 22 intowhich connector inner conductor 24 is snugly fitted. Contact sleeveportions 26 and 28 at either end of conductor 24 are adapted to receiveand make electrical connection with inner conduc-,

tors 30 and 32 of interface assembly 12 and coaxial cable 14,

respectively. Inner cylindrical surface 33 of backshell l6 and 1 contactsleeve 28 are each large enough to receive the largest individual memberof that group of cables for which a particular connector 10 is intended.Seat 46 and collar 52, each made from a conducting material, arepositioned, generally speaking, in the transition between the backshelland the body. These will be explained in more detail hereinafter.

A slotted, tubular insert 34 of a conductor material may be utilized tofacilitate the electrical connection with inner conductor 32 in thoseconfigurations of cable 14 within the group of cables for whichconnector 10 will be utilized for which conductor 32 is too small tosnugly fit within contact sleeve 28. The front end of connector 10,together with inner contact connector assembly 12, make up a standardinterface for connectors of a particular impedance rating. Accordingly,conductor 30 and sleeve 26 are designed to fit snugly together, and theuse of an insert such as 34 is not necessary.

Of course the front end of connector may be joined to the front end ofany other connector of same impedance rating which utilizes the samestandard interface. One nut 29, retained on body 18 by snap ring 31, isutilized to tighten the two connectors together. The nut on the otherconnector is run rearwardly off of threads 35 out of the way of thefirst nut and is merely retained on the body as a nonfunctioning part.The two connectors may be identical in the event the cables to be joinedare both within the same group of cables for which a particularconnector 10 is designed. in the event the cable falls outside of thatgroup, the second connector may be identical in concept to connector 10but have a configuration 'rearwardly. of the standard interfacewhichdiffers in dimensional detail. On the other hand, as long as the secondconnector is of the same. impedance and embodies the standard interface,

connection can be made, and the remaining structural details of thesecond connector are of no real significance.

Now that major components of connector 10, cable 14 and v the interfaceincluding assembly 12 have been described, the

remainingstructure of the connector and cable will be describedinconjunction with a description of the procedure by which the cable isprepared and joined to connector 10. in preparing cable 14 forconnection to connector 10, outer protective cover .36, outer conductor,or shield, 38, dielectric 40 and inner conductor 32 are trimmed to therelative lengths shown: These relative lengths can be readily determinedby a suitable trimming guide. An outer, substantially annular portion ofdielectric 40 is removed to form shoulder 41 and outer cylindricalsurface 42 for a purpose to be explained later.

Backshell l6, unfastened from body 18, is then dropped over the end ofcable 14 and moved along the cable until forward end 43 of the outerconductor is exposed beyond the forward end 44 of the backshell. Seat46, if not integral with backshell'16, is also placed over the end ofthe cable and positioned against shoulder 48. Slits are then cut inforward end 43 of the outer conductor by any suitable tool, such as adiagonal cutting shears. End 43 is then flared radially outwardly intothe configuration shown. The flaring may be done directly againstsurface 56 of seat 46, or against a suitable backing block, either byhand or with the assistance of a suitable flaring tool. The slits areexpanded during the flaring into notches 50.

A collar 52 having rearwardly facing surface 54 generally frustoconicalin nature and complementary to surface 56 of seat 46 and forwardlyfacing frustoconical surface 57 which fits snugly against thecomplementary surface 59 of dielectric 22 is placed on the forward sideof end 43 of outer conductor 38 of cable '14. Body 18 with mass ofdielectric 22 and connector inner conductor 24 contained therein is thenscrewed into backshell 16. This brings the end of cable inner conductor32 into position within contact sleeve 28 (or sleeve insert 34 if suchis utilized), and complementary frustoconical surfaces of shoulder 48and collar 52 into forceable engagement with flared forward end 43 ofthe cable. Complementary protuberance 58 and indentation 60 firmly gripflared end 43. The dimensions of collar 52 relative to dielectric 22 andbackshell 16 permit relative rotation of the collar with respectto thebackshell and dielectric thereby facilitating the connection of thebackshell and body and the forceable engagement of the flared end of thecable.

Cylindrical surface 42, formed by trimming cable dielectric 40 aspreviously related, fits snugly within the rearwardly extending tubularportion 62 of dielectric mass 22, the function of these interfittingportions of dielectric being to increase the air gap spark path betweenthe inner and outer conducting members of the cable and connector; Itwill be noted that a similar arrangement is provided at the front end ofbody 18 and interface 12.

It can be seen from the foregoing, then, that frustoconical surface 57inits position longitudinally between inner cylindrical surfaces 33 of thebackshell and 64 of the body serves as a transition for the outerconductor of the coaxial link including cable 14 and connector 10. Theinner surface of the outer conductor of the cable-connector assemblyexpands from outer conductor 38 through that transition to inner surface64 of body 18. It will be noted that the various expansions andcontractions in the size of the outer surface of the inner conductorfinds correlative changes in the size of the inner surface of the outerconductor throughout connector 10. Those skilled in the connector artwill appreciate that such correlation is necessary in order to minimizedistortion of the intelligence in its transmission through theconnector, i.e., impedance mismatch.

In the event it is desired that the connector be sealed from theatmosphere, or be liquid or gas tight, suitable means such as jam nut66, bushing 68, tubular seal 70, made of a deformable material such asrubber, and set screw 72 may be provided at the rearward end ofbackshell 16. As is apparent from the drawing, screwing jam nut 66 intothe rearward end of backshell 16 by means of complementary threads 74forces bushing 68 against seal 70 thereby deforming it in a longitudinaland radially inward direction until it comes into sealing engagementagainst the outer surface of cable 14. Suitable means, not shown, may beprovided on the backshell for introducing gas under pressure, ifdesired.

It is to be understood that although the phrase .the same or similarnominal size has been used herein to describe a group of cables withwhich a single connector configuration according to the invention may beused, it is not intended by such usage that any particular connectoraccording to the invention is necessarily limited to application to anyone particular nominal size" that may have attained, or may hereafterattain recognition in the connector art. For instance, it will bereadily apparent to those skilled in this art that one connector inaccordance with the invention would be satisfactory for a groupincluding cables of one-quarter,.three-eights, one-half inch and othersimilar nominal sizes with, of course, the same electricalcharacteristics.

While the foregoing describes the fundamental novel features of theinvention as applied to a preferred embodiment, it will be understoodthat various omissions, substitutions and/or changes may be made bythose skilled in the art within the principle and scope of the inventionas expressed in the appended claims.

What is claimed is:

1. In a connector for coaxial cables of the RF type, a combination whichpermits one connector to be suitable for use on a group of cables havingthe same impedance characteristics and similar nominal size butdifferent structural details, said combination comprising:

1. a backshell having an inner cylindrical surface of larger diameterthan the outer conductor of the largest of said group of cables,

2. a body adapted for connection to the forward end of said backshellhaving an inner cylindrical surface of larger diameter than said surfaceof said backshell and containa. a mass of dielectric material snuglyfitting within said cylindrical surface of said body and essentiallyfilling said body and having a frustoconical surface extendingrearwardly and radially inwardly from said cylindrical surface of saidbody to at least traverse the radial distance to said inner cylindricalsurface of said backshell and Y b. a central conductor contact snuglyfitting within said dielectric material, said contact having arearwardly facing tubular portion of sufficient inner diameter toreceive therewithin the largest inner conductor of said group of cables,and a forwardly facing portion adapted for connection with the innerconductor of a second connector,

and said body having a forward portion adapted for connection with asecond connector,

3. a collar of a conducting material having a forwardly facingfrustoconical surface complementary to said frustoconical surface ofsaid mass of dielectric material and extending from said innercylindrical surface of said body to at least traverse the radialdistance to said inner cylindrical surface of said backshell and havinga rearwardly facing and rearwardly and radially inwardlyextendinggenerally frustoconical surface,

4. a seat having a forwardly facing frustoconical surface complementaryto said rearwardly facing surface of said collar, said complementaryfrustoconical surfaces on said seat and collar adapted for receiving anoutwardly and forwardly flared end of the outer conductor of said cabletherebetween, the longitudinal position of said seat and .said collarbeing generally between that of said inner cylindrical surfaces of saidbackshell and said body and said complementary frustoconical surfaces ofsaid seat and said collar generally traversing the radial distancebetween said inner cylindrical surfaces,

5. complementary fastening means of said body and said backshell, theoperation of which fastens said body to said backshell and forces saidcollar and seat together against said flared end of said outerconductor.

2. The connector of claim 1 wherein said seat and collar havecomplementary protuberances and indentations in said complementaryfrustoconical surfaces for gripping the flared end of the outerconductor of the cable.

3. The connector of claim 1 wherein said complementary fastening meansare male and female screw threads.

4. The connector of claim 3 wherein said body is the male member.

5. The connector of claim 1 including means on the rearward end of thebackshell for sealing the connector from the atmosphere.

1. In a connector for coaxial cables of the RF type, a combination whichpermits one connector to be suitable for use on a group of cables havingthe same impedance characteristics and similar nominal size butdifferent structural details, said combination comprising:
 1. abackshell having an inner cylindrical surface of larger diameter thanthe outer conductor of the largest of said group of cables,
 2. a bodyadapted for connection to the forward end of said backshell having aninner cylindrical surface of larger diameter than said surface of saidbackshell and containing: a. a mass of dielectric material snuglyfitting within said cylindrical surface of said body and essentiallyfilling said body and having a frustoconical surface extendingrearwardly and radially inwardly from said cylindrical surface of saidbody to at least traverse the radial distance to said inner cylindricalsurface of said backshell and b. a central conductor contact snuglyfitting within said dielectric material, said contact having arearwardly facing tubular portion of sufficient inner diameter toreceive therewithin the largest inner conductor of said group of cables,and a forwardly facing portion adapted for connection with the innerconductor of a second connector, and said body having a forward portionadapted for connection with a second connector,
 3. a collar of aconducting material having a forwardly facing frustoconical surfacecomplementary to said frustoconical surface of said mass of dielectricmaterial and extending from said inner cylindrical surface of said bodyto at least traverse the radial distance to said inner cylindricalsurface of said backshell and having a rearwardly facing and rearwardlyand radially inwardly extending generally frustoconical surface,
 4. aseat having a forwardly facing frustoconical surface complementary tosaid rearwardly facing surface of said collar, said complementaryfrustoconical surfaces on said seat and collar adapted for receiving anoutwardly and forwardly flared end of the outer conductor of said cabletherebetween, the longitudinal position of said seat and said collarbeing generally between that of said inner cylindrical surfaces of saidbackshell and said body and said complementary frustoconical surfaces ofsaid seat and said collar generally traversing the radial distancebetween said inner cylindrical surfaces,
 5. complementary fasteningmeans of said body and said backshell, the operation of which fastenssaid body to said backshell and forces said collar and seat togetheragainst said flared end of said outer conductor.
 2. a body adapted forconnection to the forward end of said backshell having an innercylindrical surface of larger diameter than said surface of saidbackshell and containing: a. a mass of dielectric material snuglyfitting within said cylindrical surface of said body and essentiallyfilling said body and having a frustoconical surface extendingrearwardly and radially inwardly from said cylindrical surface of saidbody to at least traverse the radial distance to said inner cylindricalsurface of said backshell and b. a central conductor contact snuglyfitting within said dielectric material, said contact having arearwardly facing tubular portion of sufficient inner diameter toreceive therewithin the largest inner conductor of said group of cables,and a forwardly facing portion adapted for connection with the innerconductor of a second connector, and said body having a forward portionadapted for connection with a second connector,
 2. The connector ofclaim 1 wherein said seat and collar have complementary protuberancesand indentations in said complementary frustoconical surfaces forgripping the flared end of the outer conductor of the cable.
 3. Theconnector of claim 1 wherein said complementary fastening means are maleand female screw threads.
 3. a collar of a conducting material having aforwardly facing frustoconical surface complementary to saidfrustoconical surface of said mass of dielectric material and extendingfrom said inner cylindrical surface of said body to at least traversethe radial distance to said inner cylindrical surface of said backshelland having a rearwardly facing and rearwardly and radially inwardlyextending generally frustoconical surface,
 4. a seat having a forwardlyfacing frustoconical surface complementary to said rearwardly facingsurface of said collar, said complementary frustoconical surfaces onsaid seat and collar adapted for receiving an outwardly and forwardlyflared end of the outer conductor of said cable therebetween, thelongitudinal position of said seat and said collar being generallybetween that of said inner cylindrical surfaces of said backshell andsaid body and said complementary frustoconical surfaces of said seat andsaid collar generally traversing the radial distance between said innercylindrical surfaces,
 4. The connector of claim 3 wherein said body isthe male member.
 5. The connector of claim 1 including means on therearward end of the backshell for sealing the connector from theatmosphere.
 5. complementary fastening means of said body and saidbackshell, the operation of which fastens said body to said backshelland forces said collar and seat together against said flared end of saidouter conductor.